package common;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

public class FlowLayout extends ViewGroup{
	
	  //存储所有子View  
    private List<List<View>> mAllChildViews = new ArrayList<>();  
    //每一行的高度  
    private List<Integer> mLineHeight = new ArrayList<>();  
      
    public FlowLayout(Context context) {  
        this(context, null);  
        // TODO Auto-generated constructor stub  
    }  
    public FlowLayout(Context context, AttributeSet attrs) {  
        this(context, attrs, 0);  
        // TODO Auto-generated constructor stub  
    }  
    public FlowLayout(Context context, AttributeSet attrs, int defStyle) {  
        super(context, attrs, defStyle);  
        // TODO Auto-generated constructor stub  
    }  
    @Override  
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  
        // TODO Auto-generated method stub  
          
        //父控件传进来的宽度和高度以及对应的测量模式  
        int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);  
        int modeWidth = MeasureSpec.getMode(widthMeasureSpec);  
        int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);  
        int modeHeight = MeasureSpec.getMode(heightMeasureSpec);  
          
        //如果当前ViewGroup的宽高为wrap_content的情况  
        int width = 0;//自己测量的 宽度  
        int height = 0;//自己测量的高度  
        //记录每一行的宽度和高度  
        int lineWidth = 0;  
        int lineHeight = 0;  
          
        //获取子view的个数  
        int childCount = getChildCount();  
        for(int i = 0;i < childCount; i ++){  
            View child = getChildAt(i);  
            //测量子View的宽和高  
            measureChild(child, widthMeasureSpec, heightMeasureSpec);  
            //得到LayoutParams  
            MarginLayoutParams lp = (MarginLayoutParams) getLayoutParams();  
            //子View占据的宽度  
            int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;  
            //子View占据的高度  
            int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;  
            //换行时候  
            if(lineWidth + childWidth > sizeWidth){  
                //对比得到最大的宽度  
                width = Math.max(width, lineWidth);  
                //重置lineWidth  
                lineWidth = childWidth;  
                //记录行高  
                height += lineHeight;  
                lineHeight = childHeight;  
            }else{//不换行情况  
                //叠加行宽  
                lineWidth += childWidth;  
                //得到最大行高  
                lineHeight = Math.max(lineHeight, childHeight);  
            }  
            //处理最后一个子View的情况  
            if(i == childCount -1){  
                width = Math.max(width, lineWidth);  
                height += lineHeight;  
            }  
        }  
        //wrap_content  
        setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width,  
                modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height);  
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);  
    }  
      
    @Override  
    protected void onLayout(boolean changed, int l, int t, int r, int b) {  
        // TODO Auto-generated method stub  
        mAllChildViews.clear();  
        mLineHeight.clear();  
        //获取当前ViewGroup的宽度  
        int width = getWidth();  
          
        int lineWidth = 0;  
        int lineHeight = 0;  
        //记录当前行的view  
        List<View> lineViews = new ArrayList<View>();  
        int childCount = getChildCount();  
        for(int i = 0;i < childCount; i ++){  
            View child = getChildAt(i);  
            MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();  
            int childWidth = child.getMeasuredWidth();  
            int childHeight = child.getMeasuredHeight();  
              
            //如果需要换行  
            if(childWidth + lineWidth + lp.leftMargin + lp.rightMargin > width){  
                //记录LineHeight  
                mLineHeight.add(lineHeight);  
                //记录当前行的Views  
                mAllChildViews.add(lineViews);  
                //重置行的宽高  
                lineWidth = 0;  
                lineHeight = childHeight + lp.topMargin + lp.bottomMargin;  
                //重置view的集合  
                lineViews = new ArrayList();  
            }  
            lineWidth += childWidth + lp.leftMargin + lp.rightMargin;  
            lineHeight = Math.max(lineHeight, childHeight + lp.topMargin + lp.bottomMargin);  
            lineViews.add(child);  
        }  
        //处理最后一行  
        mLineHeight.add(lineHeight);  
        mAllChildViews.add(lineViews);  
          
        //设置子View的位置  
        int left = 0;  
        int top = 0;  
        //获取行数  
        int lineCount = mAllChildViews.size();  
        for(int i = 0; i < lineCount; i ++){  
            //当前行的views和高度  
            lineViews = mAllChildViews.get(i);  
            lineHeight = mLineHeight.get(i);  
            for(int j = 0; j < lineViews.size(); j ++){  
                View child = lineViews.get(j);  
                //判断是否显示  
                if(child.getVisibility() == View.GONE){  
                    continue;  
                }  
                MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();  
                int cLeft = left + lp.leftMargin;  
                int cTop = top + lp.topMargin;  
                int cRight = cLeft + child.getMeasuredWidth();  
                int cBottom = cTop + child.getMeasuredHeight();  
                //进行子View进行布局  
                child.layout(cLeft, cTop, cRight, cBottom);  
                left += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;  
            }  
            left = 0;  
            top += lineHeight;  
        }  
          
    }  
    /**  
     * 与当前ViewGroup对应的LayoutParams  
     */  
    @Override  
    public LayoutParams generateLayoutParams(AttributeSet attrs) {  
        // TODO Auto-generated method stub  
          
        return new MarginLayoutParams(getContext(), attrs);  
    }  

}
